Since the advent of electronic circuits, the miniaturization of transistors and logic devices has been a universal goal to advance the capabilities and applicability of electronic devices. The roadblocks to continued miniaturization are well recognized and experts have urged the need to “reinvent the transistor”. A key component to miniaturization is the reduction in operating voltage. One of the alternative approaches that hat recently received attention is nanomagnet logic (NML) using a nanomagnet to switch another nanomagnet using electron spin currents.
U.S. patent application Ser. No. 13/345,588, filed Jan. 6, 2012, which is incorporated herein by reference, teaches an all-spin logic nanomagnetic circuit in which a first nanomagnet imparts its current magnetic state to a second nanomagnet via spin currents that propagate through a spin coherent channel between the nanomagnets. Referring briefly to FIG. 1, a schematic block diagram of such an all-spin logic device 10 is shown. The device 10 includes a first nanomagnet 12, a second nanomagnet 14, and a spin-coherent channel 16. Each of the nanomagnets 12, 14 has one of two spin or magnetic “states”. The circuit 10 is a simplified circuit in which the current state of the first nanomagnet 12 can be propagated onto the second nanomagnet 14 via application of a bias voltage to both nanomagnets.
In particular, upon application of the bias voltages, the bias voltage interacts with the current magnetic state of the first nanomagnet 12 to impart a spin current onto the spin coherent channel 16. The spin current has a magnetic polarity that corresponds to the magnetic state of the first nanomagnet 12. Thus, the spin current carries the information that is stored in the first nanomagnet 12. The spin current propagates to the second nanomagnet 14. The operation of the spin current and the bias voltage on the second nanomagnet 14 causes the second nanomagnet 14 to assume the “state” of the first nanomagnet 12.
A drawback to the circuit shown in FIG. 1 is that spin currents are not suitable for transmission through ordinary conductors, and require a specifically designed spin-coherent channel 16. Moreover, the spin currents have limited range within the spin-coherent channel 16, particularly at room temperature and elevated temperatures. The limitations on the propagation of spin currents renders the combinations of such devices impracticable.
Accordingly, there is a need for a practical implementation of a nanomagnet device that avoids at least some of the shortcomings of all-spin logic nanomagnetic devices and allows for versatility and scalable circuits.